Toronto police say 90 people were arrested and 257 charges laid after authorities conducted raids targeting 43 marijuana dispensaries across the city on Thursday.

Chief Mark Saunders said search warrants were executed after letters were sent out to store fronts on May 18 advising them of city zoning bylaw violations and operating outside Canada’s medical marijuana regulations.

A city spokesperson said 78 property owners out of a “known” 83 dispensaries had been given notices by the city Wednesday stating they were in violation of zoning bylaws.

Those found in violation could face charges and extensive fines if they continued to operate.

The Trudeau government has said it plans to introduce legislation next year that will legalize marijuana across the country, but until then it’s still considered an illegal substance for recreational purposes.

Toronto’s Municipal Licensing and Standards department has also issued letters to landlords of buildings where dispensaries were operating warning those running afoul of zoning bylaws that they must come into compliance by Saturday.

Saunders said the raid operation was not an attack on medical marijuana and that those with a prescription can still have access to the drug.

He further added the proximity of the dispensaries to schools and local residences was also a cause for alarm.

Marc Emery — Canada’s self-proclaimed “Prince of Pot” who served five years in a U.S. prison for selling marijuana seeds from Canada to American customers — was leading the protest, holding a sign that read “Dispensaries are indispensable.”